The Analytical Core will provide support to Center investigators for the structural and quantitative analysis of eicosanoids. Assay methodology based on capillary column gas chromatography/electron capture negative ion chemical ionization mass spectrometry will be available for high sensitivity quantitative analyses. Lower sensitivity assays will be carried out using gas chromatography/electron ionization mass spectrometry. Structural analyses will be carried out using one of the nine mass spectrometers that are available in the Core. Ionization techniques that are available include, electron ionization, liquid secondary ion, electrospray ionization and desorption chemical ionization. We propose to develop new methods for the routine analysis of eicosanoids based on microbore LC in combination with electrospray and tandem mass spectrometry. Ultimately, it is anticipated that this methodology could replace gas chromatography/mass spectrometry as the method of choice for quantitative analyses of eicosanoids. In addition, we propose to explore the use of tandem mass spectrometry for carrying out the structural elucidation of novel eicosanoids. The single quadrupole instruments maintained by Core personnel will also be available to individual Center investigators should they want to carry out their own analyses. Investigators will be trained in instrument operation when necessary. Advice on the use of appropriate ionization techniques and column selection will be provided by personnel in the Core. The Core will also provide a resource for the synthesis of eicosanoid metabolites and stable isotope standards for use in stable isotope dilution assays. Structural confirmation of new metabolites will be carried out by chemical synthesis.